title: Intestine-Specific Mttp Deletion Increases the Severity of Experimental Colitis and Leads to Greater Tumor Burden in a Model of Colitis Associated Cancer.
abstract: Gut derived lipid factors have been implicated in systemic injury and inflammation but the precise pathways involved are unknown. In addition, dietary fat intake and obesity are independent risk factors for the development of colorectal cancer. Here we studied the severity of experimental colitis and the development of colitis associated cancer (CAC) in mice with an inducible block in chylomicron secretion and fat malabsorption, following intestine-specific deletion of microsomal triglyceride transfer protein (Mttp-IKO).
  
  
  
  Mttp-IKO mice exhibited more severe injury with ∼90% mortality following dextran sodium sulfate (DSS) induced colitis, compared to <20% in controls. Intestinal permeability was increased in Mttp-IKO mice compared to controls, both at baseline and after DSS administration, in association with increased circulating levels of TNFα. DSS treatment increased colonic mRNA expression of IL-1β and IL-17A as well as inflammasome expression in both genotypes, but the abundance of TNFα was selectively increased in DSS treated Mttp-IKO mice. There was a 2-fold increase in colonic tumor burden in Mttp-IKO mice following azoxymethane/DSS treatment, which was associated with increased colonic inflammation as well as alterations in cytokine expression. To examine the pathways by which alterations in fatty acid abundance might interact with cytokine signaling to regulate colonic epithelial growth, we used primary murine myofibroblasts to demonstrate that palmitate induced expression of amphiregulin and epiregulin and augmented the increase in both of these growth mediators when added to IL-1βor to TNFα.
  
  
  
  These studies demonstrate that Mttp-IKO mice, despite absorbing virtually no dietary fat, exhibit augmented fatty acid dependent signaling that in turn exacerbates colonic injury and increases tumor formation.
authors.affiliation: Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, United States of America.
authors.forename: Yan
authors.initials: Y
authors.lastname: Xie
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Matsumoto
authors.forename: Ilke
authors.initials: I
authors.lastname: Nalbantoglu
authors.forename: Thomas A
authors.initials: TA
authors.lastname: Kerr
authors.forename: Jianyang
authors.initials: J
authors.lastname: Luo
authors.forename: Deborah C
authors.initials: DC
authors.lastname: Rubin
authors.forename: Susan
authors.initials: S
authors.lastname: Kennedy
authors.forename: Nicholas O
authors.initials: NO
authors.lastname: Davidson
mesh_terms: D000818:Animals; D001397:Azoxymethane / Q000633:toxicity; D002352:Carrier Proteins / Q000235:genetics* / Q000378:metabolism; D002478:Cells, Cultured; D003092:Colitis / Q000139:chemically induced / Q000150:complications / Q000473:pathology*; D003106:Colon / Q000378:metabolism / Q000473:pathology; D003110:Colonic Neoplasms / Q000235:genetics / Q000473:pathology*; D016264:Dextran Sulfate / Q000633:toxicity; D004195:Disease Models, Animal; D005243:Feces / Q000737:chemistry; D020381:Interleukin-17 / Q000235:genetics / Q000378:metabolism; D053583:Interleukin-1beta / Q000235:genetics / Q000378:metabolism; D007422:Intestines / Q000473:pathology*; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D058628:Myofibroblasts / Q000166:cytology / Q000378:metabolism; D012720:Severity of Illness Index; D047368:Tumor Burden / Q000235:genetics; D014409:Tumor Necrosis Factor-alpha / Q000097:blood
chemical_list: D002352:Carrier Proteins; D020381:Interleukin-17; D053583:Interleukin-1beta; D014409:Tumor Necrosis Factor-alpha; C106092:microsomal triglyceride transfer protein; D016264:Dextran Sulfate; D001397:Azoxymethane